There are currently several solutions being proposed for long-range connectivity to Internet of Things (IoT) devices for remote-sensing or dense urban environments. SigFox, LoRa, and Cellular providers are all deploying wireless networks for low-data rate and low-power applications. However, these technologies utilize unlicensed ISM bands or paid licensed bands where propagation losses and absorption are high. Therefore in order to achieve very long-range transmissions, they use a high uplink transmission power (>13 dBm) and high receiver sensitivity values on the order of −140 dBm. In order to mitigate these requirements, a transmission scheme is proposed that uses the unlicensed Multi-Use Radio Service (MURS) band to provide a low-power solution for wide-area coverage for the IoT. This enables communication at distances >50 km with low power radios by benefiting from the low-loss propagation characteristics at the lower frequencies.
In this disclosure, a long range digital transmitter is presented for the MURS band that is frequency and data rate agile, as a low-power solution for remote IoT connectivity in multipath rich environments. While reference is made to this particular frequency band, it is understood that the broader aspects of this disclosure apply to other frequency bands as well.
This section provides background information related to the present disclosure which is not necessarily prior art.